There are many known drive mechanisms for human-powered vehicles. Known drive mechanisms are of the type which are found in a conventional bicycle, which transmits rotary motion from the front crank of a bicycle, powered by the rider's feet, to the driving wheel of the bicycle, which is generally the rear wheel. Various forms of gear mechanisms, such as the well-known nested gear with chain derailleur. Various forms of ratcheting gear drive mechanisms are known, such as those described in Jones's earlier U.S. Pat. No. 4,861,055, granted Aug. 29, 1989, for DRIVE MECHANISM, U.S. Pat. No. 4,925,200, granted May 15, 1990, for a TRICYCLE DRIVE MECHANISM, and U.S. Pat. No. 5,829,772, Nov. 3, 1998, for a RIDE-ON, HUMAN-POWERED VEHICLE DRIVE AND STEERING MECHANISM, and the references cited therein. Other drive mechanisms are known which go back into the mid-1800's.
The above-identified earlier patents disclosed human-powered vehicles (HPVs) which were primarily intended for use by young riders. While such HPVs may be simply enlarged and strengthened to accommodate adult riders, such up-sizing may present problems of disproportionate size and strength for adult riders, who, if in good physical condition, may over-stress an up-scaled HPV, resulting in damage to the HPV and possible injury to the rider. HPVs designed for young riders are generally kept simple, to facilitate use by riders whose motor skills are still developing. Adult HPVs may incorporate more complex systems and gearing suitable for use by adult riders, whose motor skills are presumably fully developed. Thus, the need for an HPV incorporating features of the earlier designs and also constructed for an adult.
One of the ongoing complaints of physically fit individuals is that there are very few fitness activities which translate well between indoor and outdoor locations. Running indoors does not have the same feel as running outdoors. A stationary bike or rowing machine does not perform in the same way that a bicycle or scull does. Placing a conventional bicycle on a dynamometer-type device does not provide the same feel as does riding a bicycle on a street or trail. Rowing machines do not duplicate the characteristics of a racing shell.